Where does “grammaticosyntactic” come from?

grammaticosyntactic (English) comes from English syntactic, from Ancient Greek συντακτικός, from Ancient Greek συντάσσω, from Ancient Greek σῠν-, from Ancient Greek σύν, from Proto-Hellenic *ksún — beside, with.

grammaticosyntactic (English): Relating to grammar and syntax

Definitions

Relating to grammar and syntax

Ancestry of “grammaticosyntactic”, step by step

Step	Language	Word	Meaning
1	English	syntactic	Of, related to or connected with syntax;...
2	Ancient Greek	συντακτικός	putting together, composing
3	Ancient Greek	συντάσσω	arrange together”, “to order
4	Ancient Greek	σῠν-	together; with, together
5	Ancient Greek	σύν	beside, with
6	Proto-Hellenic	*ksún	beside, with

Every word from Proto-Hellenic *ksún →Every word from Ancient Greek σῠν- →Every word from Ancient Greek σύν →